WO2008053662A1

WO2008053662A1 - Process for the production of laminate-type soft magnetic sheets

Info

Publication number: WO2008053662A1
Application number: PCT/JP2007/069435
Authority: WO
Inventors: Keisuke Aramaki; Junichiro Sugita; Morio Sekiguchi
Original assignee: Sony Chemical & Information Device Corporation
Priority date: 2006-10-31
Filing date: 2007-10-04
Publication date: 2008-05-08
Also published as: KR20090023413A; HK1133949A1; CN101536125B; US20090110587A1; CN101536125A; KR101119446B1; US8864929B2

Abstract

The invention provides a process which comprises laminating thin soft magnetic sheets prepared by coating method and which makes it possible to produce a laminate-type soft magnetic sheet reduced both in the variation of sheet thickness and in the variation of magnetic permeability. The process comprises the step (A) of applying a soft magnetic composition comprising as the essential components a flaky soft magnetic powder, an acrylic rubber having glycidyl groups, an epoxy resin, a latent curing agent for epoxy resin, and a solvent to a release substrate, drying the composition at a temperature (T1) at which substantially no curing reaction of the composition occurs, and removing the release substrate to obtain a curable soft magnetic sheet; the step (B) of laminating two or more curable soft magnetic sheets prepared by the step (A) to form a laminate; the step (C) of compressing the laminate at a temperature (T2) at which substantially no curing reaction occurs with a linear-load laminator under linear loads P1, P2 and P3 (P1<P2<P3) successively; and the step (D) of compressing the resulting laminate at a temperature (T3) at which curing reaction occurs with a planar-load press to cure the laminate properly and thus form a laminate-type soft magnetic sheet.

Description

Specification

Method for producing laminated soft magnetic sheet

Technical field

[0001] The present invention relates to a method for producing a soft magnetic sheet having excellent magnetic characteristics and small thickness change.

Background art

[0002] Soft magnetic sheets used in various electronic devices are generally manufactured by a kneading and rolling method. In this method, flat soft magnetic powder, rubber, and a binder such as chlorinated polyethylene are kneaded at a predetermined ratio with a kneader, and the resulting kneaded product is rolled to a predetermined thickness with an apparatus such as a calender roll, and further required. Accordingly, a single layer soft magnetic sheet is obtained by heat-crosslinking the binder. This method has the advantage that the soft magnetic powder can be filled at a high density, the soft magnetic powder can be oriented in the in-plane direction by rolling, and the sheet thickness can be easily adjusted.

[0003] However, in the case of the kneading and rolling method, since the soft magnetic powder is distorted during kneading, the magnetic properties of the soft magnetic powder itself are reduced, and the magnetic permeability of the soft magnetic sheet cannot be increased. There is a problem. Further, there has been a problem that the magnetic permeability is lowered due to a change in the sheet thickness in a high temperature or high temperature and high humidity environment.

[0004] Therefore, instead of the kneading and rolling method, a soft magnetic sheet is manufactured by a coating method in which the soft magnetic powder is less likely to be distorted (Patent Document 1). In this method, a liquid composition for forming a soft magnetic sheet composed of flat soft magnetic powder, rubber, resin and solvent is applied on a release substrate and dried to obtain a sheet thickness at high temperature and high temperature and high humidity. A soft magnetic sheet with little change is obtained.

Patent Document 1: Japanese Unexamined Patent Publication No. 2000-243615

Disclosure of the invention

Problems to be solved by the invention

[0005] However, the coating method is suitable for producing a soft magnetic sheet having a relatively thin sheet thickness, but is not suitable for producing a relatively thick soft magnetic sheet. This is thick This is because when applied, uneven coating thickness occurs and drying becomes difficult immediately. For this reason, the present inventors blended a curable resin and a curing agent thereof with a liquid composition for forming a soft magnetic sheet, and prepared a curable thin / soft magnetic sheet by a coating method. An attempt was made to make the soft magnetic sheet into a laminated type by temporarily pressing the sheet at a relatively low temperature and then pressing the sheet at a relatively high temperature. However, the laminated soft magnetic sheet made by laminating thin soft magnetic sheets made by the coating method is relatively thick manufactured by the kneading and rolling method, although the thickness change of each thin soft magnetic sheet is small. Similar to the single-layer soft magnetic sheet, there is a problem in that the sheet thickness increases in a high temperature or high temperature and high humidity environment, and the magnetic permeability decreases.

[0006] The present invention is intended to solve the above-described problems of the prior art, in which a plurality of thin / soft magnetic sheets prepared by a coating method are laminated, and the sheet thickness change is suppressed and transparent. It is an object of the present invention to provide a method capable of producing a laminated soft magnetic sheet having a small variation in magnetic susceptibility. Means for solving the problem

[0007] The present inventor relates to a laminated soft magnetic sheet prepared by laminating thin soft magnetic sheets prepared by a coating method, and changes in a direction in which the sheet thickness increases in a high temperature or high temperature and high humidity environment. Two reasons were considered as the reasons why the permeability decreased. On the one hand, air is taken in between the thin soft magnetic sheets constituting the laminated soft magnetic sheet, and the sheet thickness may increase due to the expansion of the air due to the high temperature. There is a possibility that the distortion generated in the flat soft magnetic powder is relaxed by the high temperature, and the sheet thickness is increased by shrinking the resin portion constituting the sheet.

[0008] The present inventors have assumed that the former is the main factor, and when a relatively high pressure and pressure are applied during temporary thermocompression bonding of a plurality of soft magnetic sheets, the sheet thickness cannot be ignored. I got the knowledge that it will change. In addition, assuming that the latter is the main factor, when applying relatively low pressure and pressure during temporary thermal bonding of multiple soft magnetic sheets, the knowledge that the sheet thickness will still change at a level that cannot be ignored. Obtained.

[0009] In order to achieve the object of the present invention, the present inventors have not been able to simply apply a relatively high pressure or a low pressure at the time of temporary thermocompression bonding. Using a specific soft magnetic composition, we studied in detail the heating pattern and pressure application pattern for the laminate of thin soft magnetic sheets formed from it. As a result, the above-mentioned purpose can be achieved by pre-bonding at three stages of linear pressure, low, medium, and high, at a temperature at which thermosetting does not proceed, and then finally pressing with surface pressure at a temperature at which thermosetting proceeds. As a result, the present invention has been completed.

That is, the present invention is a method for producing a laminated soft magnetic sheet, which comprises the following steps (A) to (D):

(A) A soft magnetic composition formed by mixing at least a flat soft magnetic powder, an acrylic rubber having a glycidyl group, an epoxy resin, a latent curing agent for epoxy resin, and a solvent is formed on a release substrate. And substantially free of curing reaction of the soft magnetic composition! /, Drying at a temperature T1, removing the release substrate! /, Obtaining a curable soft magnetic sheet;

(B) preparing two or more curable soft magnetic sheets and laminating them to obtain a laminate;

(C) At the temperature T2 at which the curing reaction does not substantially occur, the obtained laminate is subjected to line pressure Pl, line pressure P2, and line pressure P3 (where PK P2 <P3) using a laminator that applies line pressure. And sequentially compressing with;

(D) Step of obtaining a laminated soft magnetic sheet by compressing the compressed laminate with a press machine that applies a surface pressure at a temperature Τ3 at which the curing reaction subsequently occurs

A manufacturing method characterized by comprising:

The invention's effect

[0011] According to the present invention, a specific soft magnetic composition for forming a soft magnetic sheet is used, and the heating pattern and pressure application pattern for the laminate of thin soft magnetic sheets formed therefrom are used for thermosetting. Temporarily press-bond with low, medium and high linear pressures at temperatures that do not progress, and then press-bond with surface pressure at temperatures where thermosetting proceeds. For this reason, the change in the sheet thickness can be suppressed even in a high temperature or high temperature and high humidity environment, and as a result, the magnetic permeability can be prevented from decreasing.

Brief Description of Drawings

FIG. 1 is an electron micrograph of a cross section of a laminated soft magnetic sheet of Example 1.

FIG. 2 is an electron micrograph of a cross section of the laminated soft magnetic sheet of Comparative Example 1.

FIG. 3 is an electron micrograph of a cross section of the laminated soft magnetic sheet of Comparative Example 2. FIG. 4 is an electron micrograph of a cross section of the laminated soft magnetic sheet of Comparative Example 3.

FIG. 5 is an electron micrograph of a cross section of the laminated soft magnetic sheet of Comparative Example 4.

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] The method for producing a laminated soft magnetic sheet of the present invention has at least the following steps (A) to (D). It demonstrates for every process.

[0014] Process (A)

A soft magnetic composition formed by mixing at least a flat soft magnetic powder, an acrylic rubber having a glycidyl group, an epoxy resin, a latent curing agent for epoxy resin, and a solvent is applied onto a release substrate, The soft magnetic composition is dried at a temperature T1 at which the curing reaction does not substantially occur, and the release substrate is removed to obtain a curable soft magnetic sheet.

[0015] As a method for applying the soft magnetic composition onto the release substrate, a known method such as a doctor blade coating method or a comma coater coating method can be used. The coating thickness is a force that can be appropriately determined according to the use of the curable soft magnetic sheet and the number of laminated layers. Usually, the coating thickness is applied so that the dry thickness is 50 to 200 Hm.

[0016] The soft magnetic composition is applied to the release substrate and then dried, and then the release substrate is removed. The force S to obtain a curable soft magnetic sheet S, and the drying is caused by the curing reaction of the soft magnetic composition. Dry at a temperature T1 that does not substantially occur. In addition, the reason for drying at a temperature T1 at which the curing reaction of the soft magnetic composition does not substantially occur is that the compressibility deteriorates as the curing reaction progresses, and the one that does not rise and the curing reaction progresses is compressed. Then, it is because the thickness change in a high temperature and high humidity environment becomes large. Here, “substantially no curing reaction” means not only when no curing reaction occurs at all, but also within a range that does not impair the effects of the invention. This means that the crosslinking reaction is uniformly performed in the final step. An example of a specific means for substantially preventing the curing reaction is to set the temperature T1 to a temperature lower by 5 ° C or more than the curing reaction start temperature. The specific temperature T1 varies depending on the composition of the soft magnetic composition, and is usually 130 ° C or lower. As a specific method of drying, a known method using a hot air drying furnace, an electric heating furnace, an infrared heating furnace or the like can be employed.

[0017] In the soft magnetic composition, a soft magnetic powder having a flat shape (flat soft magnetic powder) is used. To do. By arranging the flat soft magnetic powder in a two-dimensional in-plane direction, high magnetic permeability and large specific gravity can be realized.

[0018] As a raw material of the flat soft magnetic powder, any soft magnetic alloy can be used, for example, magnetic stainless steel ^ 6-—8-31 alloy), Sendust ^ 6-31-8-1 alloy), Permalloy (Fe—Ni alloy), Key copper (Fe—Cu—Si alloy), Fe—Si alloy, Fe—Si—B (—Cu—Nb) alloy, Fe—Si—Cr—Ni alloy, Fe— Examples include Si—Cr alloys, Fe—Si—Al—Ni—Cr alloys, and ferrites. Among these, Fe—Si—A1 alloy or Fe—Si—Cr—Ni alloy can be preferably used from the viewpoint of magnetic properties.

[0019] Regarding these soft magnetic alloys, when used for RFID communication, the real part of the complex relative permeability (permeability) and the imaginary part of the complex relative permeability with a relatively large value of i '(magnetic Loss), 1 "is preferable to use a relatively small value. This prevents the magnetic field emitted from the antenna coil for RFID communication from being converted into eddy currents in the metal body, thereby improving the communication performance. Improved.

[0020] Further, as the flat soft magnetic alloy, in order to reduce the value of "for the purpose of reducing eddy current loss", it is preferable to use one having a relatively large resistance. In this case, the composition of the soft magnetic alloy For example, in the case of an Fe—Si—Cr alloy, the Si ratio is preferably 9 to 15% by weight.

[0021] As the flat soft magnetic powder, a soft magnetic powder having a flat shape is used. Preferably, the average particle diameter is 3.5 to 90 111, and the average thickness is 0.3 to 3 · O ^ m. The average particle diameter is preferably 10 to 50 111 and the average thickness is 0.5 to 2.5 m. Therefore, the flatness is preferably set to 8 to 80, more preferably 15 to 65. In order to make the size of the flat soft magnetic powder uniform, classification may be performed using a sieve or the like as necessary. In order to increase the magnetic permeability of the soft magnetic material, the particle size of the flat soft magnetic powder is increased to reduce the spacing between the particles, and the aspect ratio of the flat soft magnetic powder is increased to increase the aspect ratio of the soft magnetic sheet. It is effective to reduce the influence of the demagnetizing field.

[0022] The tap density and the specific surface area (BET method) of the flat soft magnetic powder are in inverse proportion to each other. When the non-surface area increases, the value of 'does not need to be increased. Since there is a tendency, those numerical ranges are set to a preferable range. In particular Preferably the tap density (or 0 · 55-1. 45g / ml, more preferably (or 0 · 65-1. 40g / mU to this setting, while preferably it surface area (or 0. 40- 1. 20m ² / g, more preferably (set to 0.65 to 1.00 m ² / g.

[0023] Further, as the flat soft magnetic powder, for example, a soft magnetic powder subjected to a coupling treatment using a coupling agent such as a silane coupling agent may be used. By using the soft magnetic powder subjected to the coupling treatment, it is possible to enhance the reinforcing effect at the interface between the flat soft magnetic powder and the binder resin, and to improve the specific gravity and corrosion resistance. As the coupling agent, for example, silane, γ-glycidoxypropinoremethinolegetoxysilane, etc. can be used. The above-described coupling treatment may be performed on the soft magnetic powder in advance, or when the flat soft magnetic powder and the binder resin are mixed, they are mixed at the same time, so that the force coupling treatment is performed. You may do it.

[0024] If the amount of the flat soft magnetic powder used in the soft magnetic composition is too small, the intended magnetic properties cannot be obtained, and if it is too large, the amount of the binder resin is relatively reduced and the moldability is lowered. Preferably, it is 70 to 90% by weight, more preferably 80 to 85% by weight in the soft magnetic composition excluding the solvent.

[0025] The soft magnetic composition uses acrylic rubber as a rubber component in order to impart good flexibility and heat resistance to the laminated soft magnetic sheet. This acrylic rubber always has one or more glycidyl groups in order to improve compatibility with the epoxy resin. Specific examples include ΕΑ-ΑΝ, ΒΑ-ΕΑ-ΑΝ, ΒΑ-ΑΝ, ΒΑ-ΜΜΑ, and the like.

[0026] If the amount of the acrylic rubber used in the soft magnetic composition is too small, sufficient heat processability cannot be obtained, and if it is too large, the rubber elasticity becomes too large and the heat processability deteriorates. 9 to 16% by weight, more preferably 12 to 14% by weight.

[0027] The soft magnetic composition uses an epoxy resin in order to impart good heat processability and dimensional stability to the laminated soft magnetic sheet. Specific examples include phenol nopolac, tetraglycidyl phenol, o-cresol novolak, tetraglycidylamine, bisphenol 8, bisphenol F, bisphenol A glycidyl ether, and the like. [0028] If the amount of the epoxy resin used in the soft magnetic composition is too small, sufficient heat processability cannot be obtained, and if it is too large, flexibility is impaired. Therefore, the soft magnetic composition excluding the solvent is preferable. 1.0 to 6.0 wt ^_0/0 in, more preferably from 1.5 to 4. 0 weight ^_0/0.

[0029] In the soft magnetic composition, specific examples of using the latent curing agent for epoxy resin to cure the epoxy resin include amine imidazole and polyamide phenolic anhydride.

[0030] If the use amount of the latent curing agent for epoxy resin in the soft magnetic composition is too small, the reliability of the product is lowered (decrease in storage characteristics), and if it is too much, the life of the paint is lowered and the sheet line is reduced. Therefore, the amount is preferably 3 to 100 parts by weight, more preferably 10 to 40 parts by weight, based on 100 parts by weight of the epoxy resin.

[0031] As the solvent, an ordinary general-purpose solvent can be used. For example, alcohols such as ethanol, n-propanol, isopropyl alcohol (IPA), n-butyl alcohol, ethyl acetate, n-butyl acetate, etc. Esters, acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), ketones such as cyclohexanone, ethers such as tetrahydrofuran (THF), ethyl acetate sorb, n-butyl sorb sorb, cellosolve acete General-purpose solvents such as cellosolves such as carbonates and aromatic hydrocarbons such as toluene, xylene, and benzene can be used. The amount used can be appropriately selected according to the type of composition of the soft magnetic composition, the coating method, and the like.

[0032] As the release substrate, a normal release substrate can be used. For example, a polyester sheet whose surface has been subjected to a silicone peeling treatment can be used.

[0033] The soft magnetic composition can be prepared by uniformly mixing the above-described components by a conventional method.

[0034] Step (B)

Prepare two or more curable soft magnetic sheets obtained in step (A) and laminate them to obtain a laminate. The number of layers is determined by the use of the laminated soft magnetic sheet. Further, when stacking, it is preferable to dispose release sheets on both sides of the laminate of soft magnetic sheets. As the release sheet in this case, a polyester sheet or the like whose surface has been subjected to silicone release treatment can be used. [0035] Step (C)

Next, the laminate obtained in the step (B) is subjected to a line pressure Pl, a line pressure P2 and a line pressure P3 (provided that P1 <P2 <P3) Sequential compression and temporary pressure bonding. By performing the temporary pressure bonding in this way, it is possible to prevent the occurrence of defective products due to sheet displacement, to improve the reliability by air bleeding, and to prevent stretching.

[0036] In this step, the reason why the soft magnetic sheet is pressurized at a temperature T2 at which a curing reaction does not substantially occur is to cause a uniform crosslinking reaction in a state where a surface pressure is applied. Here, “substantially no curing reaction” means that, as in the case of step (A), it is insignificant if it does not impair the effects of the invention only when no curing reaction occurs. This means that a curing reaction may occur and means that the crosslinking reaction is uniformly performed in the final step. An example of a specific means for substantially preventing the curing reaction is to set the temperature T2 to a temperature 5 ° C or more lower than the curing reaction start temperature. The specific temperature T2 varies depending on the composition of the soft magnetic composition constituting the soft magnetic sheet, but is usually 70 to 130 ° C, preferably 70 to 100 ° C. As a specific heating method, a known method using a hot air drying furnace, an electric heating furnace, an infrared heating furnace, or the like can be employed.

[0037] The reason why the linear pressure is applied by the laminator that applies the linear pressure is to prevent air entrainment. The reason for applying gradually from low linear pressure to high linear pressure in three stages is to effectively vent the sheet according to the softness, density and density of the sheet, and not to cause sheet misalignment. Because. Specific examples of the laminator include a metal roll, a rubber roll, and a combination of a metal roll and a rubber roll.

[0038] The specific values of Pl, P2, and P3 are different forces depending on the soft magnetic sheet material, the number of laminated layers, etc. P 1 is preferably 2 to 10 kgf / cm, more preferably 3 to 8 kgf / cm, P2 Preferably, it is 10-20 kgf / cm, more preferably 12-; 18 kgf / cm, P3 force, preferably 20-50 kgf / cm, more preferably 25-45 kgf / cm.

[0039] Also, if the line speed of the laminator in this process is too fast, heat will not be transmitted and compression will not proceed, causing problems such as poor bonding, and if it is too slow, production efficiency will deteriorate and cost will increase. Preferably 0.;! To 5. Om / min, more preferably 0.5 to 3. Om / min [0040] Process (D)

Subsequently, the compressed laminate obtained in the step (C) is subjected to main pressure bonding while being compressed and cured by a press machine applying a surface pressure at a temperature T3 at which a curing reaction occurs, and then the laminated soft magnetic material of the present invention. Get a sheet. In the obtained laminated soft magnetic sheet, the change in sheet thickness is suppressed even under a high temperature or high temperature and high humidity environment, and as a result, the magnetic permeability does not decrease.

In this step, the reason why the compressed laminate is pressurized at the temperature T3 at which the curing reaction occurs is to advance the crosslinking reaction in a state where the magnetic powders are arranged in the plane. The specific temperature T3 varies depending on the composition of the soft magnetic composition, and is usually 140 to 200 ° C., preferably 150 to 180 ° C. Further, the reason for applying the pressure by the surface pressure is to perform crosslinking in a state where the surface is uniformly pressurized. The surface pressure value varies depending on the soft magnetic sheet material, the number of laminated layers, etc. (preferably 10 to 60 kgf / cm ² , more preferably 15 to 40 kgf / cm ² ).

[0042] The laminated soft magnetic sheet obtained by the above manufacturing method is one in which the change in sheet thickness is suppressed and the variation in magnetic permeability is small.

Example

Hereinafter, the present invention will be specifically described with reference to examples.

[0044] Example 1

(Creation of soft magnetic sheet)

Flat soft magnetic powder? ^ 550 parts by weight, acrylic rubber with glycidyl group (SG80H'3, Nagase ChemteX Corporation) 83 parts by weight, epoxy resin (Epicoat 1031S, Japan Epoxy Resin Co., Ltd.) 23 A soft magnetic composition comprising 1 part by weight, a latent curing agent for epoxy resin (HX3748, manufactured by Asahi Kasei Chemicals Corporation), 6.9 parts by weight, 270 parts by weight of toluene, and 120 parts by weight of ethyl acetate. Was prepared. Regarding the cumulative particle size D m) of the flat soft magnetic powder used, D10 was 9.4 to 111, D50 was 23.9 to m, and D90 was 49.1 to m. The force and bulk density were 0.6 g / cc, and the tap density was 1.30 g / cc.

[0045] The composition was applied on a release polyester (PET) substrate with a coater, dried at a temperature of less than 80 ° C, then further dried at 100 ° C, and 100 m on the release PET substrate. Thickness of soft A magnetic sheet was obtained.

[0046] (Preparation of laminate of soft magnetic sheets)

Peeling from the above-mentioned soft magnetic sheet The PET base material was peeled off to obtain a single-layer soft magnetic sheet. Four single-layer soft magnetic sheets were prepared and laminated to obtain a laminate.

[0047] (Temporary pressure bonding of laminate of soft magnetic sheets)

The resulting laminate is applied once to a laminator (manufactured by Sony Chemical & Information Device Co., Ltd.) with a roll temperature of 70 ° C at a line speed of 0.5 m / min and a linear pressure of 3.3 kgf / cm. Then, it was passed twice with a linear pressure of 14.8 kgf / cm, and then further passed twice with a linear pressure of 29 · 54 kg / cm to perform temporary pressure bonding.

[0048] (Preparation of laminated soft magnetic sheet)

Next, the temporarily press-bonded laminate was compressed with a vacuum press device (manufactured by Kitagawa Seiki) at 165 ° C for 10 minutes at a pressure of 24.9 kgf / cm ² to obtain the laminated soft magnetic sheet of Example 1. Obtained. Figure 1 shows a cross-sectional view of this laminated soft magnetic sheet. From Fig. 1, magnetic powder is packed in high density and aligned in the plane direction!

[0049] Comparative Example 1

(Creation of soft magnetic sheet)

In the same manner as in Example 1, a soft magnetic sheet having a thickness of 100 m was obtained on a peeled PET substrate.

[0050] (Creation of soft magnetic sheet laminate)

[0051] (Temporary pressure bonding of laminate of soft magnetic sheets)

The obtained laminate was applied to a laminator (manufactured by Sony Chemical & Information Device Co., Ltd.) set at a roll temperature of 70 ° C at a line speed of 0.5 m / min and a linear pressure of 3.3 kgf / cm 5 times. A temporary pressure bonding was performed.

[0052] (Preparation of laminated soft magnetic sheet)

Next, the temporarily bonded laminate was compressed with a vacuum press (made by Kitagawa Seiki) at a pressure of 24.9 kgf / cm ² to obtain a laminated soft magnetic sheet. Figure 2 shows a cross-sectional view of this laminated soft magnetic sheet. Figure 2 shows that there are slightly more voids at the stack interface. [0053] Comparative Example 2

(Creation of soft magnetic sheet)

[0054] (Preparation of laminate of soft magnetic sheets)

[0055] (Temporary pressure bonding of laminate of soft magnetic sheets)

The obtained laminate was applied to a laminator (manufactured by Sony Chemical & Infomation Device Co., Ltd.) with a roll temperature set at 70 ° C at a line speed of 0.5m / min and a linear pressure of 29 / 5kgf / cm. A temporary pressure bonding was performed.

[0056] (Preparation of laminated soft magnetic sheet)

Next, the temporarily bonded laminate was compressed with a pressure of 24.9 kgf / cm ² using a vacuum press (made by Kitagawa Seiki) to obtain a laminate type soft magnetic sheet of Comparative Example 2. Figure 3 shows a cross-sectional view of this laminated soft magnetic sheet. Figure 3 shows that there are places with high density and high orientation and places with low density and poor orientation.

[0057] Comparative Example 3

(Creation of soft magnetic sheet)

[0058] (Preparation of laminate of soft magnetic sheets)

Peeling from the above-mentioned soft magnetic sheet The PET substrate was peeled off to obtain a single-layer soft magnetic sheet. Four single-layer soft magnetic sheets were prepared and laminated to obtain a laminate. Figure 4 shows a cross-sectional view of this laminated soft magnetic sheet. From Figure 4, it forces ^s I force voids (air) remains large, Ru.

[0059] (Preparation of laminated soft magnetic sheet)

Next, the laminate was compressed at a pressure of 24 · 9 kgf / cm ² with a vacuum press (manufactured by Kitagawa Seiki) without being temporarily crimped to obtain a laminate type soft magnetic sheet of Comparative Example 3.

[0060] Comparative Example 4

(Creation of soft magnetic sheet) In the same manner as in Example 1, a soft magnetic sheet having a thickness of 100 m was obtained on a peeled PET substrate.

[0061] (Preparation of laminate of soft magnetic sheets)

[0062] (Preparation of laminated soft magnetic sheet)

Next, the laminate was compressed with a pressure of 37.4 kgf / cm ² with a vacuum press (manufactured by Kitagawa Seiki) without provisional pressure bonding, and a laminated soft magnetic sheet of Comparative Example 4 was obtained. Figure 5 shows a cross-sectional view of this laminated soft magnetic sheet. From Fig. 5, the high density area and the air (air) area are clearly separated!

[0063] (Evaluation)

First, the thickness (tl) and the permeability μ ′ were measured on the obtained laminated soft magnetic sheet. The magnetic permeability is preferably 38 or more practically. In addition, the thickness (t2) of the soft magnetic sheet after being held for 240 hours (hr) in a high-temperature and high-humidity environment at 85 ° C and 60% Rh was measured, and the thickness change rate [(tl -t2) X 100 / t2] (%) was calculated. The rate of change in thickness is close to 0! /, More preferred! / ヽ (In Table 1, G is indicated when the rate of change in thickness is less than 2.0, and NG is indicated otherwise). Furthermore, regarding the occurrence rate (%) of sheet misalignment, the number of sheets causing misalignment was calculated from the number of sheets prepared. The results obtained are shown in Table 1.

[0064] [Table 1]

As can be seen from Table 1, in the case of the laminated soft magnetic sheet of Example 1, the permeability was obtained by passing the laminate of the soft magnetic sheet through a laminator under three-stage pressure conditions before the vacuum press. The thickness change at 85 ° C, 60Rh%, 240hr was less than 2% / J, and ft]. Even when the cross section of the soft magnetic sheet was observed, it was found that air entered! /, !!, and the lamination interface was not confirmed. When 50 laminated soft magnetic sheets were produced, the incidence of defective products due to sheet misalignment was 0%.

[0066] In the case of the laminated soft magnetic sheet of Comparative Example 1, the magnetic permeability can be increased by passing the soft magnetic sheet through a laminator before vacuum pressing, and the sheet at 85 ° C, 60Rh%, 240hr. The change in thickness was 3% or more, and the change in thickness was larger than that in Example 1. When 50 sheets were produced, the sheet deviation was 0 sheets, and the incidence of defective products was 0%.

[0067] In the case of the laminated soft magnetic sheet of Comparative Example 2, the magnetic permeability can be increased by passing the soft magnetic sheet through a laminator before vacuum pressing. The thickness at 85 ° C, 60Rh%, 240hr The change in thickness was 2% or more, and the change in thickness was larger than that in Example 1. When 50 sheets were produced, the sheet shift was 12 sheets, and the incidence of defective products was high.

[0068] In the case of the laminated soft magnetic sheet of Comparative Example 3, since it was not passed through a laminator before being compressed by a vacuum press, as shown in FIG. 4, each soft layer of the single layer constituting the laminated soft magnetic sheet was used. It can be seen that there is a gap at the interface of the magnetic sheet. Further, the change in thickness at 85 ° C., 60 Rh%, and 240 hr was 2% or more, and the change in thickness was larger than that in Example 1. When 50 sheets were produced, the defective product generation rate due to misalignment of the sheets was 0%.

[0069] In the case of the laminated soft magnetic sheet of Comparative Example 4, it is possible to obtain the same magnetic permeability S as Example 1 by increasing the pressure of the vacuum press S, and the force that reduces the gap at the laminated interface. Since it is compressed with excessive pressure, internal strain remains, which is considered to be one factor that causes the thickness to change in a high-temperature and high-humidity environment. The thickness change at 85 ° C., 60 Rh%, and 240 hr was 2% or more, which was larger than that in Example 1. When 50 sheets were produced, the defective product generation rate due to misalignment of the sheets was 0%.

Industrial applicability

[0070] In the production method of the present invention, a specific soft magnetic composition for forming a soft magnetic sheet is used, and a heating pattern and a pressure application pattern for a laminate of thin soft magnetic sheets formed therefrom are used. Temporarily press-bond at low, medium, and high linear pressures at temperatures where curing does not proceed, and then perform final pressure bonding at surface pressure at temperatures where thermosetting proceeds. For this reason, high temperature Or, the change in the thickness of the laminated soft magnetic sheet can be suppressed even in a high temperature and high humidity environment, and as a result, the magnetic permeability can be prevented from decreasing. The soft magnetic sheet is useful as a magnetic flux converging body in RFID systems such as non-contact type IC cards and IC tags, or as a general electromagnetic wave absorber. In other words, it is useful as a noise electromagnetic wave absorber for electronic devices such as RFID flexible shield materials and portable digital cameras.

Claims

The scope of the claims

[1] A method for producing a laminated soft magnetic sheet, comprising the following steps (A) to (D):

(C) Line temperature Pl, line pressure P2 and line pressure P3 (where PK P2 <P3) are applied to the obtained laminate with a laminator that applies line pressure at temperature T2 at which curing reaction does not substantially occur. And sequentially compressing with; and

The manufacturing method characterized by having.

[2] The P1 force is 2 to 10 kgf / cm, the P2 force is 10 to 20 kgf / cm, the P3 force is 20 to 50 kgf / cm, and the surface pressure is 10 to 60 kgf / cm ² Production method.

[3] T1 is 50-90 ° C, T2 force S70-; 130 ° C, T3 is 140-200 ° C

The production method according to 1 or 2.

[4] The line speed of the laminator in step (C) is 0 · !! ~ 5m / min.

The manufacturing method described in 3! /.

[5] The production method according to any one of claims 1 to 4, wherein, in the steps (C) and (D), a release sheet is disposed on each side of the laminate, and the release sheet is released and compressed.